The liftoff of space shuttle Discovery has been delayed beyond the launch window that begins February 3rd. Program managers will target a new launch date after modifications, repairs and tests on Discovery's external tank are complete.

Technicians in the Vehicle Assembly Building at the Kennedy Space Center are seen here making changes to more than 30 of the tank's support beams, called stringers. Crews also are repairing newly-discovered cracks similar to those found after Discovery's Nov. 5 launch attempt. More work may be undertaken after additional data is reviewed.

Meanwhile, NASA engineers at the Marshall Space Flight Center are using optical and electron microscopes and other resources to track down the cause of the cracks.

Greg Jerman:

"We'll take little pieces of the part that failed and retest them and then compare them to known good material to try and understand what differences there are between what a nominal system would be versus the failed system that we had."

Shuttle managers are looking at potential launch dates for Discovery in late February.

"This was originally a 90-day mission; only three months and here we are some seven years later and we're still exploring and we're still discovering on the surface with these rovers."

This month the twin rovers, Spirit and Opportunity, are completing their seventh year on Mars. While Spirit remains immobile and in a slumber following the harsh Martian winter, Opportunity rolls on, investigating rocks on the lip of a football-sized crater. These images taken by the Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment, the HiRISE camera, show Opportunity perched on the western edge of the Santa Maria crater. The rover is slated to explore Santa Maria over the next several months. Scientists hope that, as the Martian landscape warms up, Spirit may rouse itself and begin to communicate again. Once Opportunity is finished at the Santa Maria crater, it'll begin a slow but steady nearly two-year trek towards Endeavour crater.

John Callas:

"...We know there are these clay minerals present in the rim of Endeavour Crater that is suggestive of ancient water on Mars that was of neutral ph. Neutral water is what astrobiologist assess that life started in and so the fact that there is evidence of ancient neutral water on Mars is very exciting for the bio-potential of the planet."

NASA's Associate Administrator for Education, Leland Melvin toured three NASA field centers in California, taking time to speak with staff about the agency's education goals and their encouragement of middle school students to pursue studies in science, technology, engineering and mathematics.

Leland Melvin: "Get the tools in your head, the reading, the writing, the math, the science, all the things your teachers are teaching you right now, so that you can do anything you want to; anything you can put your mind to you can do."